System can detect 9600 proteins or DNA molecules simultaneously
David L. Shenkenberg
As a research associate in the laboratory of Dr. Suzanne Lentzsch at the University of Pittsburgh Medical Center, Rentian Feng has been studying proteins called cytokines in myeloma, a type of cancer that arises from special white blood cells in bone marrow.
Cytokines are a class of proteins that white blood cells use to signal other white blood cells to grow and develop more rapidly to fight disease. However, when white blood cells become myeloma cells, cytokines help the cancer cells grow and develop out of control. Therefore, Feng and colleagues have been investigating compounds that can inhibit cytokine production in myeloma.
The scientists found that myeloma cells can produce 32 cytokines, eight of which are critical. Then they studied those eight, trying to determine which chemical can inhibit their production.
They found that a compound traditionally used to treat parasitic worms can inhibit cytokine production in myeloma cells and induce apoptosis, a suicide mechanism that cells have when they know that they have become cancerous. The scientists observed the effect at micromolar but not nanomolar dosages. Feng said that the identity of the antiparasitic compound with anticancer properties is still a secret because the work has not yet been published in a peer-reviewed journal.
Figure 1. The Luminex xMAP system enables analysis of 100 times more proteins than a traditional ELISA (enzyme-linked immunosorbent assay). Courtesy of R. Feng.
To study the cytokines, the researchers used the xMAP system from Luminex Corp. of Austin, Texas. Feng said that its overall usefulness depends on the application. The system works with conventional 96-well plates for a total of up to 9600 simultaneous measurements. “In each well you can measure 100 different cytokines, [whereas] before you could only measure one in each well.”
Scientists using the system can coat up to 100 sets of tiny color-coded beads with the reagent specific to the protein or DNA that they want to detect. If scientists want to detect cytokines, they can mix the beads with antibodies for the cytokines that they want to detect. They can use secondary antibodies with fluorescent labels to quantify how many cytokines there are in a sample (Figure 2). A crucial part of the xMAP system, the Luminex 100 analyzer contains lasers that can stimulate both the dyes in the beads and the reporter dyes. Feng said that a technician can run the system.
Figure 2. The Luminex xMAP uses a unique system to analyze proteins. Courtesy of R. Feng.
In past work, Feng and colleagues discovered that the cyanidin-3-glucoside substance naturally found in blackberries can prevent and fight cancer, as reported in the June 23, 2006, issue of the Journal of Biological Chemistry. For this discovery, Feng received the Charles C. Shepard Science Award from the Centers for Disease Control and the National Institute for Occupational Safety and Health.
As described in the paper, the investigators irradiated skin cells with UV light and found that the blackberry compound prevents the activation of several genes known to play a role in cancer. They also grafted lung tumors onto mice and found that the blackberry compound reduced the ability of the lung tumors to grow and spread.
Contact: Rentian Feng, University of Pittsburgh Medical Center, Pittsburgh; e-mail: firstname.lastname@example.org.
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